Linear Technology DC2142A Quick setup guide

1
dc2142af
DEMO MANUAL DC2142A
Description
LTC3875EUJ & LTC3874IUFD
High Efficiency, Single-Output Synchronous
Buck Converter with Very Low DCR Inductor
Demonstration circuit 2142A is a high efficiency, high
density, 4-phase synchronous buck converter with a 4.5V
to 14V input range. It can supply 120A maximum load
current at a 1.0V output. This demo board incorporates
the LTC3875EUJ and LTC3874IUFD controllers.
The LTC
®
3875 is a feature-rich dual phase synchronous
buck controller with very low DCR current sensing capa-
bility, on-chip drivers and remote output voltage sens-
ing. The LTC3874 is a compact dual phase synchronous
buck phase extender with very low DCR current sensing
capability, on-chip drivers and immediate response to
master IC's fault.
This board is setup with 0.32mΩ DCR inductor. The tem-
perature compensation function guarantees accurate cur-
rent limit over awide temperature range with DCR sensing.
TheDC2142canprovidehighefficiency,highpowerdensity
and compact solutions for telecom and datacom systems, L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
performance summary
industrial and medical instruments, DC power distribution
systems and computer systems. The LTC3875 is available
in a 40-pin 6mm ×6mm QFN package. The LTC3874 is
available in a 28-lead (4mm ×5mm) QFN Package.
To shut down the converter, set the RUN pin voltage be-
low 1.4V(SW1: OFF). Use the JP1 jumper to select burst
mode, pulse skipping mode or forced continuous mode
operation at light load. Switching frequency is preset at
about 400kHz, and it can be easily modified from 250kHz
to 770kHz. An on-board dynamic circuit is also available
for transient test. The LTC3875 and LTC3874 data sheets
give a complete description of these parts, and must be
read in conjunction with this DC2142A quick start guide
Design files for this circuit board are available at
http://www.linear.com/demo/DC2142A
Specifications are at TA= 25°C
PARAMETER CONDITIONS VALUE
Input Voltage Range 4.5V to 14V
Output Voltage, VOUT VIN = 4.5V to 14V, IOUT1 = 0A to 120A 1.0V ±2%
Maximum Output Current, IOUT VIN = 4.5V to 14V, VOUT1 = 1.0V 120A
Typical Efficiency, VOUT VIN = 12V, VOUT1 = 1.0 V, IOUT1 = 120A 87.4%
Typical Switching Frequency 400kHz
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dc2142af
DEMO MANUAL DC2142A
Quick start proceDure
Demonstration circuit 2142A is easy to set up to evaluate
the performance of the LTC3875EUJ and LTC3874IUFD.
Refer to Figure 1 for the proper measurement equipment
setup and follow the procedure below:
1. With power off, connect the input power supply to VIN
(4.5V to 14V) and GND (input return).
2. Connect the 1.0V output load between VOUT and GND
(Initial load: no-load).
3. Connect the DVMs to the input and outputs. Set default
jumper position: JP1: CCM; SW1: ON.
4. Turnonthe input powersupplyand check fortheproper
output voltages. VOUT should be 1.0V ±2%.
5. Once the proper output voltages are established, ad-
just the loads within the operating range and observe
the output voltage regulation, ripple voltage and other
parameters.
Note: When measuring the output or input voltage ripple,
donot usethe long ground lead on the oscilloscopeprobe.
See Figure 2 for the proper scope probe technique. Short,
stiff leads need to be soldered to the (+) and (–) terminals
of an output capacitor. The probe’s ground ring needs to
touch the (–) lead and the probe tip needs to touch the
(+) lead.
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dc2142af
DEMO MANUAL DC2142A
Quick start proceDure
Figure 1. Proper Measurement Equipment Setup
Figure 2. Measuring Output Voltage Ripple
+ –
VOUT GND
C40
–
+
+–
VOUT
VIN
4.5V TO 14V
1mΩ
dc2142a F01
+
–
LOAD
(0A ~ 120A)
+
–
+
–
+
–
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dc2142af
DEMO MANUAL DC2142A
Quick start proceDure
0
70
75
80
85
90
95
20 40 60
LOAD CURRENT (A)
EFFICIENCY (%)
80 100
dc2142a F03
120
Figure 3. Efficiency vs Load Current at VIN = 12V, VOUT = 1.0V, fSW = 400kHz
Figure 4. Thermal Performance at VIN = 12V, VOUT = 1.0V, IOUT = 120A, 200PFM Forced Air Flow
Efficiency vs Load Current, VOUT = 1.0V
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dc2142af
DEMO MANUAL DC2142A
Quick start proceDure
Figure 5. Current Sharing vs Load Current at VIN = 12V, VOUT = 1.0V, fSW = 400kHz
Figure 6. Output Voltage Ripple at VIN = 12V, VOUT = 1.0V, IOUT = 120A
Current Sharing vs Load Current, VOUT = 1.0V
0
0
5
10
15
20
25
30
35
20 40 60
LOAD CURRENT (A)
CURRENT SHARING (A)
80 100
dc2142a F05
120
CHANNEL 4
CHANNEL 3
CHANNEL 2
CHANNEL 1
±3.6%
VOUT (20MHz BW) [5mV/DIV]
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dc2142af
DEMO MANUAL DC2142A
Quick start proceDure
Figure 7. Transient Performance at VIN = 12V, VOUT = 1.0V, IOUT = 30A ~ 60A
VOUT(20MHzBW)[20mV/DIV]
30A TO 60A LOAD STEP
parts List
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 8 CIN1, CIN2, CIN3, CIN4, CIN5, CIN6,
CIN7, CIN8 CAP, 1210, 10µF, 20%, 35V X5R AVX 1210DD106MAT2A
2 14 COUT1, COUT2, COUT6, COUT7,
COUT9, COUT12, COUT13, COUT14,
COUT19, COUT20, COUT24, COUT25,
C39, C40
CAP, 1210, 100µF, 20%, 6.3V X5R TDK C3225X5R0J107M
3 12 COUT3, COUT4, COUT5, COUT8,
COUT10, COUT11, COUT15, COUT16,
COUT17,COUT18, COUT22, COUT23
CAP, 7343, 330µF, 20%, 6.3V POSCAP SANYO 6TPF330M9L
4 3 C3, C25, C29 CAP, 0603, 1µF, 20%, 25V X5R AVX 06033D105KAT2A
5 2 C1, C2 CAP, 270µF, 20%, 16V OSCON PANASONIC 16SVPC270M
6 4 C4, C30, C31, C46 CAP, 0603, 4.7µF, 10%, 10V X5R AVX 0603ZD475KAT2A
7 1 C5 CAP, 0603, 10nF, 10%, 16V X7R AVX 0603YC103KAT2A
8 5 C7, C8, C18, C32, C36, CAP, 0603, 0.1µF, 10%, 25V X5R AVX 06033C104KAT2A
9 6 C10, C12, C20, C24, C33, C35 CAP, 0603, 220nF, 10%, 25V X7R TDK C1608X7R1E224K
10 1 C15 CAP, 0603, 220pF, 5%, 50V C0G AVX 06035A221JAT2A
11 1 C16 CAP, 0603, 2.2nF, 5%, 50V C0G MURATA GRM1885C1H222JA01D
12 1 C34 CAP, 0603, 100pF, 10%, 16V X7R AVX 0603YC101KAT2A
13 1 D1, D2, D3, D4 DIODE, SCHOTTKY 30V, 100mA CENTRAL SEMI CMDSH-3-TR
14 4 L1, L2, L3, L4 IND, 0.25µH WÜRTH ELEKTRONIK 744301025
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dc2142af
DEMO MANUAL DC2142A
parts List
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
15 4 Q1, Q5, Q10, Q15 XSTR, POWER MOSFET INFINEON BSC050NE2LS
16 4 Q3, Q7, Q13, Q17 XSTR, POWER MOSFET INFINEON BSC010NE2LSI
17 1 Q19 XSTR, N-CHANNEL DMOS FET FAIRCHILD 2N7002A
18 2 Q20, Q21 XSTR, MOSFET, N-CHANNEL 30V VISHAY SUD50N04-8M8P-4GE3
19 1 R1 RES, 0603, 20kΩ, 5%, 1/10W VISHAY CRCW060320K0JNEA
20 1 R2 RES, 0603, 3.01kΩ, 1%, 1/10W VISHAY CRCW06033K01FKEA
21 1 R3 RES, 0603, 1kΩ, 5%, 1/10W VISHAY CRCW06031K00JNEA
22 3 R4, R51, R85 RES, 0603, 2.2Ω, 5%, 1/10W VISHAY CRCW06032R20JNEA
23 2 R6, R14 RES, 0603, 10Ω, 1%, 1/10W VISHAY CRCW060310R0FKEA
24 4 R8, R28, R58, R66 RES, 0603, 715Ω, 1%, 1/10W VISHAY CRCW0603715RFKEA
25 2 R9, R27 RES, 0603, 3.57kΩ, 1%, 1/10W VISHAY CRCW06033K57FKEA
26 13 R10, R13, R24, R50, R53, R54, R56,
R57, R59, R60, R61, R65, R67 RES, 0603, 0Ω, JUMPER VISHAY CRCW06030000Z0EA
27 1 R12 RES, 0603, 13.3kΩ, 1%, 1/10W VISHAY CRCW060313K3FKEA
28 1 R17 RES, 0603, 20kΩ, 1%, 1/10W VISHAY CRCW060320K0FKEA
29 1 R21 RES, 0603, 4.02kΩ, 1%, 1/10W VISHAY CRCW06034K02FKEA
30 3 R33, R42, R69 RES, 0603, 100kΩ, 1%, 1/10W VISHAY CRCW0603100KFKEA
31 1 R45 RES, 0603, 5kΩ, 5%, 1/10W VISHAY CRCW06035K00JNED
32 2 R46, R47 RES, 0603, 10kΩ, 1%, 1/10W VISHAY CRCW060310K0FKEA
33 1 R63 RES, 0603, 75kΩ 5% 1/10W VISHAY CRCW060375K0JNEA
34 1 R102 RES, 0603, 237kΩ, 1%, 1/10W VISHAY CRCW0603237KFKEA
35 1 SW1 SWITCH, SUBMINATURE SLIDE C&K JS202011CQN
36 1 U1 IC, DUAL, 2-PHASE, SYNCHRONOUS
REGULATORS LINEAR TECH. LTC3875EUJ#PBF-ES
37 1 U2 IC, POLYPHASE STEP-DOWN
SYNCHRONOUS SLAVE CONTROLLER LINEAR TECH. LTC3874IUFD#PBF
Additional Demo Board Circuit Components
1 0 COUT27, COUT28, COUT29, COUT30,
COUT31, COUT32, COUT33, COUT34,
COUT35, COUT36, COUT37, COUT38,
COUT39, COUT40, COUT41, COUT42,
COUT43, COUT44, COUT45, COUT46
CAP, 1210 OPTION OPTION
2 0 C9, C11, C26, C27, C28 CAP, 0603 OPTION OPTION
3 4 C43, C44, C47, COUT21, CAP, 0603, 1µF, 20%, 25V X5R AVX 06033D105KAT2A
4 1 C37 CAP, 0805, 10µF, 10%, 16V X5R MURATA GRM21BR61C106KE15L
5 1 C38 CAP, 0805, 22µF, 10%, 10V X5R TDK C2012X5R1A226K
6 1 C42 CAP, 0603, 150pF, 5%, 50V NPO AVX 06035A151JAT2A
7 2 C41, C45 CAP, 0603, 0.1µF, 10%, 25V X5R AVX 06033C104KAT2A
8 1 C48 CAP, 0603, 22pF, 2%, 50V C0G MURATA GRM1885C1H220GA01D
9 1 D5 DIODE, SCHOTTKY 30V, 100mA CENTRAL SEMI CMDSH-3-TR
10 1 L5 IND, 3.3µH WÜRTH ELEKTRONIK 744043003
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dc2142af
DEMO MANUAL DC2142A
parts List
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
11 0 Q2, Q4, Q6, Q8, Q11, Q14, Q16, Q18 XSTR, POWER MOSFET OPTION OPTION
12 2 R88, R92 RES, 0603, 20kΩ, 5% 1/10W VISHAY CRCW060320K0JNEA
13 2 R68, R87 RES, 0603, 0Ω, JUMPER VISHAY CRCW06030000Z0EA
14 0 RN1, RN2 THERMISTOR, OPTION OPTION
15 0 R5, R7, R11, R15, R16, R18, R19,
R34, R35, R37, R39, R40, R41, R43,
R44, R48,R49, R52, R55, R62, R64,
R70, R76, R101, R104, R105
RES, 0603 OPTION OPTION
16 2 R77, R94 RES, 0603, 10kΩ, 1% 1/10W VISHAY CRCW060310K0FKEA
17 1 R80 RES, 0603, 187kΩ, 1% 1/10W VISHAY CRCW0603187KFKEA
18 1 R83 RES, 0603, 23.2kΩ, 1% 1/10W VISHAY CRCW060323K2FKEA
19 1 R89 RES, 0603, 3.3Ω, 1%, 1/10W VISHAY CRCW06033R30FNEA
20 1 R90 RES, 0603, 154kΩ, 1% 1/10W VISHAY CRCW0603154KFKEA
21 1 R91 RES, 0603, 1MΩ, 5% 1/10W VISHAY CRCW06031M00JNEA
22 1 R93 RES, 0603, 681kΩ, 1% 1/10W VISHAY CRCW0603681KFEA
23 2 R95, R100 RES, 0603, 301Ω, 1% 1/10W VISHAY CRCW0603301RFKEA
24 1 R96 RES, 0603, 82.5Ω, 5% 1/10W VISHAY CRCW060382R5FKEA
25 2 R97, R98 RES, 2512, 0.01Ω, 1% 1W VISHAY WSL2512R0100FEA
26 1 R99 RES, VARIABLE 5k BOURNS 3386P-1-502-LF
27 1 UD1 IC, OSCILLATOR WITH SPREAD SPECTRUM
MODULATION LINEAR TECH. LTC6908S6-1#PBF
28 1 U3 IC, 17V, 1A, SYNCHRONOUS STEP-DOWN
REGULATOR LINEAR TECH. LTC3621EDCB-2#PBF
29 1 U4 IC, VOLTAGE-CONTROLLED PULSE WIDTH
MODULATOR LINEAR TECH. LTC6992IS6-1
30 1 U5 IC, SINGLE OP AMP LINEAR TECH. LT1803IS5
Hardware: For Demo Board Only
1 12 E1, E2, E3, E4, E5, E6, E7, E11, E13,
E14, E15, E16 TURRET MILL MAX 2501-2-00-80-00-00-07-0
2 1 JP1 HEADER, 4-PIN WURTH 620 004 111 21
3 2 JP6, JP7 HEADER, SINGLE ROW 3-PIN WURTH 620 003 111 21
4 6 J1, J2, J3, J4, J5, J6 STUD, TEST PIN PEM KFH-032-10
5 2 J7, J9 CONN, BNC, 5-PINS CONNEX 112404
6 6 LUG RING, #10 KEYSTONE 8205
7 4 MH1, MH2, MH3, MH4 STANDOFF, SNAP ON KEYSTONE 8834
8 12 NUT, BRASS 10-32 ANY #10-32
9 6 WASHER, #10 TIN PLATED BRASS ANY #10 EXT BZ TN
10 3 JP1, JP6, JP7 SHUNT WURTH 608 002 134 21
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dc2142af
DEMO MANUAL DC2142A
schematic Diagram
INTVCC1
R13 0
CIN2 10uF 1210
J6
GND
J3
VOUT
J4
GND
E2
VIN+
VFB
R47
10K
1%
J1
VIN
J2
GND
R27 3.57k 1%
C28 OPT
+C1
270uF 16V
R12
13.3k
1%
R45 5k
R39
OPT
R4 2.2
R5
OPT
REVISION HISTORY
DESCRIPTION DATE APPROVEDECO REV
YINGYI, Y .PROD3 12/31/13
C7
0.1uF
RUN
OFF
ON
SW1
1
2
3
4
5
6
C24
220nF
C11
OPT
R15 OPT
R10
0
INTVCC1
E4
VIN-
4.5V - 14V
+
COUT4 330uF 6.3V 7343
R3 1k
R7
OPT
ITH VFB
PGOOD
BST1
VO_SNS+
C16
2.2nF
E7
VO_SNS-
SIZE DATE:
IC NO. REV.
SHEET OF
TIT LE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY
Fax: [phone] Milpitas, CA 95035 Phone: [phone] McCarthy Blvd. LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
www.linear.com
3
Tuesday, Decem ber 31, 2013 1 3
HIGH EFFICIENCY POLYPHASE , SYNCHRONOUS
!"
#"$% #"&#'
N/A LTC3875EUJ / LTC3874EUFD
DEMO CIRCUIT 2142A
BUCK CONVERTER WITH VERY LOW DCR INDUCTOR
C20 220nF
E6
TK/SS
1.0V AT 120A
R17 20k
1%
R34 OPT
R42 100k
1%
E5
RUN
JP1
MODE
PS CCMBM
1
2
3
4
BST2
E13
GND
C3 1.0uF
E1
PLLIN
E3
VO_SNS+
C15 220pF
RUN
C5 10nF
COUT2 100uF 1210 6.3V
Q4 OPT
3
1
2
4
5
Q3
BSC010NE2LSI
3
1
2
4
5
R14 10 1%
R8 715 1%
VO_SNS+
C4
4.7uF
R41
OPT
C12
220nF
R21
4.02k 1%
BG2
INTVCC1
VO_SNS-
Q2 OPT
3
1
2
4
5
BG1
INTVCC1
DCR=0.32m OHM
C25
1.0uF
744301025
E11
EXTVCC
C8
0.1uF
VIN
R33 100k
1%
R9 3.57k 1%
INTVCC1
R44
OPT
RN1 OPT
12
R40
OPT C26
OPT
R19
OPT
VIN
COUT7 100uF 1210 6.3V
COUT6 100uF 1210 6.3V
VOUT
VO_SNS-
EXTVCC
R105
OPT
D1
CMDSH-3-TR
RN2 OPT
1 2
R48
OPT
R43
OPT C27
OPT
DCR=0.32m OHM
TG1
C10
220nF
R1
20K
L1 0.25uH
CIN1 10uF 1210
+
COUT8 330uF 6.3V 7343
+
COUT5 330uF 6.3V 7343
VOUT
+C2
270uF 16V
E14 PGOOD
SW1
C46 4.7uF
TK/SS
+
COUT3 330uF 6.3V 7343
INTVCC1
INTVCC1
CIN4 10uF 1210
R24 0
Q8 OPT
3
1
2
4
5
Q7
BSC010NE2LSI
3
1
2
4
5
Q6 OPT
3
1
2
4
5
744301025
C18
0.1uF
VIN
L2 0.25uH
R28 715 1%
C9
OPT
D2
CMDSH-3-TR
TG2
CIN3 10uF 1210
Q1
BSC050NE2LS
3
1
2
4
5
SW2 Q5
BSC050NE2LS
3
1
2
4
5
VO_SNS-
COUT1 100uF 1210 6.3V
EXTVCC C LKOUT
U1
LTC3875EUJ
TG2 21
SW2 20
BOOST2 22
SGND/PGND
41
BOOST1 28
SW1 30
TKSS2
8
SNSD2+ 11
TK/SS1
1
TRSET2
14
RUN1
34
RUN2
16
TCOMP2
12
ITH2
5
TAVG
13
CLKOUT 31
ITH1
4
PHASMD 32
MODE/PLLIN 33
ILIM 35
BG2 23
SNSA2+ 9
IFAST
17
VOSNS2-
7
VOSNS2+
6
ISNS2- 10
VOSNS1+
2
SNS1- 39
SNSD1+ 38
BG1 27
VOSNS1-
3
FREQ
15
ENTMPB
18
PGOOD
19
TG1 29
INTVCC 25
VIN 26
EXTVCC 24
SNSA1+ 40
TCOMP1
37
TRSET1
36
R46 10K
1%
EXTCLK
TK/SS
R2 3.01k 1%
R6 10 1%
J5
VOUT
R11 OPT
R35 OPT
R18 OPT
VIN
R37 OPT
R16
OPT
RUN
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10
dc2142af
DEMO MANUAL DC2142A
schematic Diagram
R64
OPT
BG3
VOUT
CLKOUT
R55
OPT
R49
OPT
VIN
INTVCC2
ITH
L3 0.25uH
R68
0
R63 75k
R67 0
SIZE DATE:
IC NO. REV.
SHEET OF
TIT LE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY
Fax: [phone] Milpitas, CA 95035 Phone: [phone] McCarthy Blvd. LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
www.linear.com
2
Wednesday, March 05, 2014
2 3
HIGH EFFICIENCY POLYPHASE , SYNCHRONOUS
!"
#"$% &"'#(
N/A
LTC3875EUJ / LTC3874EUFD
DEMO CIRCUIT 2142A
BUCK CONVERTER WITH VERY LOW DCR INDUCTOR
INTVCC2
CIN5 10uF 1210
R59 0 Q14
OPT
3
1
2
4
5
Q13
BSC010NE2LSI
3
1
2
4
5
Q11 OPT
3
1
2
4
5
744301025
C32
0.1uF
VIN
R53 0
R58 715 1%
R62 OPT
D3
CMDSH-3-TR
CIN6 10uF 1210
INTVCC2
R65 0
CIN8 10uF 1210
TK/SS
TG4
Q18 OPT
3
1
2
4
5
Q17
BSC010NE2LSI
3
1
2
4
5
Q16 OPT
3
1
2
4
5
744301025
VIN
C36
0.1uF
R70 OPT
R66 715 1%
CIN7 10uF 1210
D4
CMDSH-3-TR
Q10
BSC050NE2LS
3
1
2
4
5
Q15
BSC050NE2LS
3
1
2
4
5
+
COUT10
330uF 6.3V 7343
COUT9 100uF 1210 6.3V
+
COUT11
330uF 6.3V 7343
COUT12 100uF 1210 6.3V
SW4
R54 0
R61
0
R69 100k 1%
+
COUT15
330uF 6.3V 7343
COUT14 100uF 1210 6.3V
+
COUT16
330uF 6.3V 7343
COUT13 100uF 1210 6.3V
R57 0
BST4
R60 0
BG4
C40 100uF 1210 6.3V
C39 100uF 1210 6.3V
INTVCC2
EXTVCC
EXTCLK
INTVCC2
C35 220nF
VOUT
L4 0.25uH
RUN
INTVCC2
INTVCC2
C33 220nF
R52 OPT
C34
100pF
PGOOD
R56 0
Q19
2N7002A
2 3
1
R50 0
BST3
C30 4.7uF
C31 4.7uF
C29 1.0uF
COUT21 1.0uF
COUT20 100uF 1210 6.3V
COUT19 100uF 1210 6.3V
COUT25 100uF 1210 6.3V
COUT24 100uF 1210 6.3V
+
COUT22
330uF 6.3V 7343
+
COUT23
330uF 6.3V 7343
+
COUT18
330uF 6.3V 7343
+
COUT17
330uF 6.3V 7343
PGOOD
SW3
R51 2.2
U2
LTC3874IUFD#PBF
MODE0
1
ISENSE0+ 2
ISENSE0- 3
RUN0
4
RUN1
5
ISENSE1- 6
ISENSE1+ 7
MODE1
8
ITH1
9
FREQ
10
ILIM
11
SYNC
12
PHASMD
13
TG1 14
SW1 15
BOOST1 16
BG1 17
EXTVCC 18
INTVCC 19
VIN 20
BG0 21
BOOST0 22
SW0 23
TG0 24
FAULT1B 25
LOWDCR
27
ITH0
28
GND
29
FAULT0B 26
TG3
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11
dc2142af
DEMO MANUAL DC2142A
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
schematic Diagram
COUT40 OPT 1210
R104
OPT
COUT41 OPT 1210
COUT42 OPT 1210
R83 23.2K
1% COUT43
OPT 1210
C45
0.1uF
UD1 LTC6908S6-1#PBF
V+
1
GND
2
SET
3MOD 4
OUT2 5 OUT1 6
COUT44 OPT 1210
C42 150pF
J7
VOUT
1
2
R87 0
+5.5V
R94
10K 1%
R98 0.01
2512
R91 1M
COUT45 OPT 1210
PULSE
70Hz, 3% Duty Cy cle
DYNAMIC LOAD CIRCUIT
R93 681K
1%
R89 3.3 1%
R96
82.5 1%
R97 0.01 2512
INT
1% 1%
EXT
J9
1
2
IOUT STEP
R95
301
C44
1.0uF
R100
301
U5 LT1803IS5
VOUT 1
V-
2
+IN
3-IN 4
V+
5
U4 LTC6992IS6-1 MOD
1
GND
2
SET
3DIV4
V+ 5
OUT 6
R85 2.2
JP6
1
2
3
R92 20K
Q20
SUD50N04-8M8P-4GE3
C41 0.1uF
VIN
JP7
1
2
3
E15
EXT PULSE
R90
154k
R99
5K
C43 1.0uF
E16
GND
Q21
SUD50N04-8M8P-4GE3
R88 20K
EXTCLK
EXTVCC
R76 OPT
+5.5V
R80 187k 1%
OPTIONAL 5.5V BIAS
C37 10uF 16V 0805
BIAS OFF
ON
D5
CMDSH-3-TR
SIZE DATE:
IC NO. REV.
SHEET OF
TIT LE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY
Fax: [phone] Milpitas, CA 95035 Phone: [phone] McCarthy Blvd. LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
www.linear.com
2
Wednesday, March 05, 2014
3 3
HIGH EFFICIENCY POLYPHASE , SYNCHRONOUS
!"
#"$% &"'#(
N/A
LTC3875EUJ / LTC3874EUFD
DEMO CIRCUIT 2142A
BUCK CONVERTER WITH VERY LOW DCR INDUCTOR
+5.5V COUT27
OPT 1210
C47 1.0uF 25V
COUT46 OPT 1210
VOUT
INTVCC1
VOUT
VOUT
VOUT
COUT28 OPT 1210
R101
OPT
COUT29 OPT 1210
L5
3.3uH
COUT30 OPT 1210
COUT31 OPT 1210
R77 10K
1%
COUT32 OPT 1210
COUT33 OPT 1210
R102
237k
1%
744043003
COUT34 OPT 1210
COUT35 OPT 1210
COUT36 OPT 1210
C38 22uF 10V 0805
U3
LTC3621EDCB-2
SW 1
3
RUN
MODE
6
7GND
INTVCC
5
VIN
2
FB 4
COUT37 OPT 1210
COUT38 OPT 1210
C48 22pF
COUT39 OPT 1210
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12
dc2142af
DEMO MANUAL DC2142A
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
[phone] ●FAX: [phone] ●www.linear.com
 LINEAR TECHNOLOGY CORPORATION 2014
LT 0314 • PRINTED IN USA
DEMONSTRATION BOARD IMPORTANT NOTICE
Linear Technology Corporation (LTC ) provides the enclosed product(s) under the following AS IS conditions:
Thisdemonstration board(DEMO BOARD) kitbeing soldor providedby LinearTechnologyis intendedfor use forENGINEERING DEVELOPMENT
OR EVALUATION PURPOSES ONLY and is not provided by LTC for commercial use. As such, the DEMO BOARD herein may not be complete
in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety
measures typically found in finished commercial goods. As a prototype, this product does not fall within the scope of the European Union
directive on electromagnetic compatibility and therefore may or may not meet the technical requirements of the directive, or other regulations.
If this evaluation kit does not meet the specifications recited in the DEMO BOARD manual the kit may be returned within 30 days from the date
of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY THE SELLER TO BUYER AND IS IN LIEU
OF ALL OTHER WARRANTIES, EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS
FOR ANY PARTICULAR PURPOSE. EXCEPT TO THE EXTENT OF THIS INDEMNITY, NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR
ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.
The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user releases LTC from all claims
arising from the handling or use of the goods. Due to the open construction of the product, it is the user’s responsibility to take any and all
appropriate precautions with regard to electrostatic discharge. Also be aware that the products herein may not be regulatory compliant or
agency certified (FCC, UL, CE, etc.).
No License is granted under any patent right or other intellectual property whatsoever. LT C assumes no liability for applications assistance,
customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind.
LTC currently services a variety of customers for products around the world, and therefore this transaction is not exclusive.
Please read the DEMO BOARD manual prior to handling the product. Persons handling this product must have electronics training and
observe good laboratory practice standards. Common sense is encouraged.
This notice contains important safety information about temperatures and voltages. For further safety concerns, please contact a LTC applica-
tion engineer.
Mailing Address:
Linear Technology
1630 McCarthy Blvd.
Milpitas, CA 95035
Copyright © 2004, Linear Technology Corporation
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